Decontamination of the skin is a process that is incompletely understood and as a result, some decontamination procedures can make penetration of a chemical through the skin worse. Therefore, it is necessary to decontaminate the skin on a rational basis, rather than indiscriminately. Systemic toxicity from skin exposures is the combined result of two chemical characteristics -penetration of the chemical through the skin and toxic potency of the chemical. The range of penetrability and toxic potency for common industrial chemicals varies over several orders of magnitude. Even an extremely toxic chemical that does not penetrate the skin readily may not need decontamination after exposure. The purpose of this review is to provide information about systemic toxicity from skin exposures and how chemical permeability and toxicity are determined, so that an individual may evaluate the necessity for decontamination of chemicals used in his/ her specific workplace.